Since you're going to cover the landscape cloth with decorative rock, you can temporarily hold it down with stones as you're installing it. Once you have it laid out the way you want it, simply pour the rocks over and rake them out, removing the stones as you go. The weight of the rocks will keep the cloth in place. I usually fold the ends of the cloth under when I come to the border of the bed, making sure that it's butted up snugly against the wood or plastic border material. So far, no weeds have appeared where the cloth and the borders meet. If you want to stake the material down, you can use homemade hooks by cutting lengths of heavy gauge wire (or old wire coathangers) and bending in the center to make a 'U' shaped hook. Either way, your landscape cloth should stay put and supress weeds.